1. Field of the Invention
The present invention relates generally to an electromagnetic-induction system, and more particularly, relates an antenna layout and its coordinate positioning method of the electromagnetic-induction system.
2. Description of the Prior Art
Because a handwriting recognition system could replace the mouse, and is more suitable than the mouse to let the user input words and patterns by user""s hands, improvement of the handwriting recognition system is a hot and important field of current computer technology. The original intention of the handwriting recognition system is to replace the mouse. As usual, to enhance the user""s convenience, a handwriting recognition system would usually replace the mouse by both wireless pen and tablet. Herein, the pen nib of the wireless pen usually corresponds to the left button of the mouse. Conventional handwriting recognition systems have been developed for many years, but these products are applied to perform only one function, such as drawing or inputting a word.
In the conventional electromagnetic-induction systems, there are usually a digitizer tablet and a transducer/cursor in the form of a pen or a puck. As is well known, there are two operation modes for determining the position of a pointing device on the surface of a digitizer tablet, wherein one is a relative mode, and the other is an absolute mode. A mouse device operates in a relative mode. The computer sensing the inputs from a mouse recognizes only relative movements of the mouse in X and Y directions as it is slid over the surface on which it is resting. If the mouse is lifted and repositioned on the surface, no change in the signal to the computer will be detected. A common approach uses a sensing apparatus inside the mouse to develop a pair of changing signals corresponding to the longitudinal and transversal movements of the mouse. On the contrary, a cursor device in a digitizer tablet system, such as electromagnetic-induction pen, operates in an absolute mode. If a cursor device is lifted and moved to a new position on its supporting surface, its signal to a computer will change to reflect the new absolute position of the cursor device. Nowadays, various methods have been used to determine the position of a cursor device on the surface of its supporting tablet, wherein one common skill which is applied for the absolute mode is electromagnetic field sensing.
Early transducer/cursors were connected to the tablet by means of a multi-conductor cable through which the position and button/pressure information are transferred virtually without any problem. The cordless transducer/cursors in some of the prior arts have attempted to use frequency and/or phase changes to transmit the non-positional status of the transducer/cursor functions such as buttons pushed, pen pressure, or the like. However, if there is no sophisticated processing, frequency and phase changes are very prone to false reading resulting from several outside factors such as metal objects, noise, wireless electromagnetic wave and so on. These problems become more apparent, especially in a larger digitizer tablet. Improvements have also been made in the prior arts to allow a, user to use pointing devices on a digitizer tablet system in dual modes of operation that can provide information of either a relative movement or an absolute position under the control of the user.
Usually, a handwriting recognition system is a device with cordless pressure-sensitivity and electromagnetic-induction. Refer to FIG. 1, it shows a circuit block diagram of a conventional cordless pressure-sensitive and electromagnetic-induction device. Conventional cordless pressure-sensitivity and electromagnetic-induction device comprises: an electromagnetic-induction pen and a tablet. There is an oscillating circuit that consists of LC in the electromagnetic-induction pen. If the pen point is touched, the amount of inductance will be changed that results in the variation of oscillating frequency. The amount of inductance is increased when touching the pen point and increasing pressure so the variation of oscillating frequency is also increased. Therefore, the variation of the pressure on the pen point can be detected by way of the variation of oscillating frequency. There are two switches on the sidewall of the electromagnetic-induction pen, the emitted frequency of the electromagnetic-induction pen can be changed with the capacitance variation of the LC device that is produced by pushing down or setting free the switches. Furthermore, the tablet comprises a detector, -an amplifier and an analog-digital converter. In the conventional tablet, there is a detected loop in the center region of the tablet, with one-way antennas located on the double faces of the detected loop, wherein the one-way antennas are equidistantly arranged in order by way of using array. The main purpose of the one-way detected loop is only applied to receive the electromagnetic wave that is emitted by the electromagnetic-induction pen. When the electromagnetic-induction pen emits the electromagnetic wave, the one-way antennas receive the electromagnetic wave, and then the tablet can obtain correlative information by the electromagnetic induction.
Therefore, for those conventional antenna layout and signal detection methods, the obtained coordinate accuracy is normally low, hence reduces CPU efficiency and the return rate. Thus, an improvement in coordinate accuracy is still one of the most crucial goals of development in the industry.
In accordance with the above description, the present invention provides an antenna layout and its coordinate positioning method for electromagnetic induction systems, so as to increase the coordinate positioning accuracy and strengthen the efficiency of electromagnetic induction systems.
In accordance with the above description of the prior art, the present invention provides an antenna layout and its coordinate positioning method of electromagnetic-induction systems for improving the coordinate accuracy and the efficiency of the conventional electromagnetic induction systems.
An object of the present invention is to provide a coordinate positioning procedure of the electromagnetic-induction system. The present invention uses a five-stage coordinate positioning method to increase the coordinate positioning accuracy and to speed up the coordinate return rate. Thus, the present invention satisfies the industrial utility.
Another object of the present invention is to provide a five-stage coordinate positioning method of the electromagnetic-induction system. The present invention uses a coordinate calculation formula to ensure a highly accurate coordinate calculation. Hence, the present invention can reduce CPU processing time, as well as can avoid the problem of line defect when using hand-writing input, thus, can strengthen the electromagnetic induction system efficiency.
A further object of the present invention is to provide an antenna layout of the electromagnetic-induction system. The present invention uses a 4-4 distribution antenna layout the antenna layout density. Therefore, the present invention can reduce the area of printed circuit boards, thus, reducing the production time and achieving the product size reduction target. Hence, the present invention satisfies an economical efficiency.
In accordance with the above description of the objects, the present invention discloses a 4-4 distribution antenna layout and a five-stage coordinate positioning method of the electromagnetic-induction system. The 4-4 distribution antenna layout of the present invention distributes the electromagnetic induction system""s induction antennas on both sides of the printed circuit board in a equal space manner and uses two-dimension array method to form an antenna circuitry for obtaining a clearer signal when the electromagnetic field changes.
The antenna circuitries are divided into x-axis and y-axis groups. The antenna circuitries within the same group are in equal distance displacements and in the same direction, and further comprise a plurality of antenna loops. In order to allocate the antenna circuitries uniformly and to reduce the antenna layout density, each antenna |circuitry within the same direction group comprises a plurality of antenna loops. For example, an antenna circuitry consisted of four antenna loops, only three of the antenna loops surround the transmission source when a signal transmission source is placed directly above the prime region of the antenna loops. The formation of each antenna loop comprises a dense multiple duplicate self-looping method. Therefore, when the electromagnetic field changes, an antenna with more loops can induce a stronger induction signal.
Moreover, the five-stage coordinate positioning method of electromagnetic induction systems comprising, first, carrying out a first procedure, the universal scanning procedure, to confirm any signal with voltage amplitude greater than a standard minimum signal recognition value. Second, carrying out a second procedure, the mid-terrain confirmation scanning procedure, to confirm signal existence of the previous scan as well as to confirm the nearest antenna loop to the transmission source. Third, carrying out a third procedure, -a partial confirmation scanning procedure, to obtain coordinate values. And, final, using an internal micro-processing sub-circuitry of the electromagnetic-induction system to calculate an absolute coordinate.